From what I've read, The Rio Grande used these devices on all their standard guage steam power. Why did'nt they catch on with the rest of the railroad industry? Seems like they would have been the next best thing to dynamic brakes what with saving all that brake shoe wear.

From what I have read about them they were awful hard on the packing in they cylinders. I think most railroads would rather pay for cast iron shoes (back in the day) instead of taking a loco out of service to have its cylinders re packed on a regular basis.Rio Grande did it for its topography which is pretty rugged by most standards and I guess felt it was worth it in the long rn for them.